1. Technical Field
The present invention provides a system and method for managing data updates in a hierarchy of virtual copies of data. More specifically, the present invention provides a mechanism for providing an enhanced snapshot pointer.
2. Description of Related Art
In known storage subsystems that make use of instant copy operations, such as the Snapshot instant copy mechanism available from Storage Technology, Inc., data files are received from a processor and stored in back-end data storage devices by mapping the processor assigned data file identifier to a logical address that identifies the physical storage location of the data. This mapping allows instant copies of data files by creating duplicate data file pointers that reference the original data files. In this dynamically mapped virtual data storage system, the data files are referred to as a collection of “virtual tracks” and each data file is identified by unique virtual track addresses (VTAs).
Using an instant copy mechanism, such as the Snapshot instant copy mechanism, may result in many copies of the same set of pointers, i.e. a subset of the pointer table, being used in a storage subsystem. It is useful to manage these various copies of the pointers so that changes to data tracks associated with pointers in a pointer table are passed along to appropriate copies of the pointers.
Although the snapshot copy technology has eased some of the difficulty in managing data, particularly difficulties involving resource consumption due to duplicated data, the current technology is not well adapted to managing data across space. The snapshot technology is not efficient when attempting to manage data throughout a distributed environment.
Thus, the present invention is a method and system that provides an enhanced snapshot pointer that includes multiple different flags that indicate whether the enhanced pointer points directly to data or to another pointer, whether the enhanced pointer points to a local or remote location, and whether the enhanced pointer includes additional data.